Mechanical drivers (or motors) are used in a wide variety of different applications ranging from optics, microscopy, robotics, and analytical instruments. In many of these applications, it is desirable for the mechanical driver to be small in size and light in weight, while being operable to move and position one or more components within a device with moderate speed and high precision.
Semiconductor fabrication technology is being used to develop devices that include mechanical drivers that are formed with micro-electro-mechanical systems (MEMS) that have micron-scale features. Various MEMS-based devices, such as actuators, acoustic devices, filters, resonators and sensors, are formed of active materials that change in size or shape in response to applied energy, which may be in the form of an electrical field, a magnetic field, an electromagnetic field, or thermal energy. Induced strain actuators (or morphs) bend as a result of internal moments that are induced by the applied energy. Induced strain actuators convert induced strains into moments that cause the constituent active materials to bend in a controlled way. Induced strain actuators may be formed of, for example, piezoelectric materials, ferroelectric materials, electrorestrictive materials, magnetorestrictive materials, and thermally expansive materials.
Different types of MEMS-based micro-motor designs have been proposed. Many such micro-motor designs are driven by electrostatic forces. In a typical approach, the micro-motor includes a rotor and a stator. The stator includes electrodes that are placed around the rotor. A voltage differential is applied between a selected group of stator electrodes and the rotor. The voltage differential creates an electric field that rotates the rotor into alignment with the selected group of stator electrodes. The rotor is rotated continuously by powering different sets of stator electrodes in a synchronized way.
In another approach, a linear bi-directional motor is driven by one or more MEMS-based induced strain actuators. These actuators incorporate a plurality of multi-clamps that ride on and alternately engage rails that are located on the base of the motor. The multi-clamps are driven by electrically energized auxiliary actuators. The operation of the multi-clamps is synchronized with the operation of a main actuator that alternately extends and contracts. The coordinated operation the main and auxiliary actuators results in incremental movement of the multi-clamp assembly along the rails.